We use "guys" in Canada too. I don't think the word is that significant, but since it may in some cases be more associated with the younger generation LE may have released that word to convince the public that BG is much younger than initially portrayed to be. Changing sketches was a big shift, and hearing the difference in tone of voice between 'guys' and 'down the hill' helped me see BG as a younger individual.
I've often wondered about the exact terminology A&L used when talking about 'the man' behind them (from their 'girl talk' recording). I asked my teen daughters how they would differentiate between 'boy', 'guy', and 'man' if they saw a male stranger on a trail and had to describe him. Based on their responses I would think A&L would have referenced BG as a 'boy' if he appeared to be younger than themselves. I think they would have called BG a 'guy' if he appeared to be a teenager or college age male (20-something). My girls thought they would say 'man' only if he looked 'old' or 'like a dad'. A really old male they would call a 'grandpa' or 'senior'. So if in fact A&L used the term 'man' to describe the person following them, it leads me to believe that he appeared, from their perspective, to be someone 30-40. Maybe it is the clothing that is making him seem older.